As the aerospace industry seeks to reduce weight and improve fuel efficiency, thermal spray coatings are becoming increasingly important for protecting metal components from the effects of heat, wear and corrosion. Greenstone-Tech is a leading supplier of high-performance metal laser cladding and metal coatings for aerospace applications. We offer a broad range of coating materials and application methods, along with corresponding complete equipment solutions, to meet our customers’ unique needs. Our coatings are specifically designed to withstand the extreme conditions found in aircraft operations, and our experienced team of professionals has a history of success in this demanding environment.

1. Key components that require surface repair

(1) Engine components

(1.1) Turbine blades/compressor blades: Long-term exposure to high temperature, high pressure and corrosive gas environment, prone to thermal fatigue cracks or oxidation corrosion, need to be repaired by laser cladding or thermal spraying.

(1.2) Combustion chamber components: Subject to extreme temperature and thermal stress, the surface is prone to oxidation or ablation, and needs to be repaired to improve high temperature resistance.

(1.3) Turbine disk: Surface microcracks caused by high-speed rotation and thermal cycling, need to be repaired by surface cleaning and coating.

(2) Structural parts and transmission system

(2.1) Drive shafts and gears: Prone to wear or fatigue damage under high load operation, need to be repaired to restore geometric accuracy and wear resistance.

(2.2) Bearing seats and fasteners: Long-term exposure to vibration and stress, the surface is prone to wear or corrosion, need to be repaired to meet the surface roughness (Ra≤1.6μm) and bonding strength requirements.
(2.3) Hydraulic system valves: Sealing surfaces fail due to friction or corrosion, and require polishing or chemical treatment to restore sealing performance.

(3) Special alloy parts

(3.1) High elastic high temperature alloy spiral retaining rings: used for sealing and fixing, need to be repaired to meet the requirements of high temperature elasticity and corrosion resistance (such as GH2132, GH4169 alloys).

(3.2) Aircraft landing gear parts: subject to impact loads and corrosive environments, require surface repair by electroplating or shot peening.

II. Involved quality standards and key requirements

(1) GB/T 43376-2023 “Aerospace – Surface cleaning of heat-treatable and strengthened stainless steel parts”

(1.1) Scope of application: Surface cleaning of heat-treatable and strengthened stainless steel parts (such as engine blades and combustion chamber parts) before and after hot working and final processing.

(1.2) Technical requirements:

(1.2.1) Cleanliness: Remove pollutants such as oil, rust, and scale to ensure that there is no residue on the surface (visual inspection or chemical testing).

(1.2.2) Roughness: Ra≤1.6μm after final processing, otherwise bright processing (such as chemical polishing or electrolytic polishing) is required.
(1.2.3) Corrosion resistance: The protective effect of the passivation film or coating is verified by salt spray test (such as GJB 150.11A-2009).

(2) GB/T 41477-2022 “Test method for mechanical properties of metal parts repaired by laser cladding”
(2.1) Applicable objects: parts repaired by laser cladding (such as turbine blades, gears).
(2.2) Test requirements:
(2.2.1) Tensile properties: The bonding strength between the repair layer and the substrate must reach more than 90% of the raw material.
(2.2.2) Fatigue performance: The fatigue life of the repaired parts must meet the requirements of aviation conditions.

(3) GJB 10326-2021 “Specifications for High Elasticity High Temperature Alloy Spiral Retaining Rings for Aerospace”
(3.1) Material requirements: Use high temperature alloys such as GH2132 and GH4169, the chemical composition complies with GB/T 5307-2004, and the smelting temperature range is 550~650℃.
(3.2) Performance verification: Need to pass Rockwell hardness test (GB/T 230.1-2018) and salt spray test (GJB 150.11A-2009).

(4) ISO 8075:1985 (adopted standard)
(4.1) International benchmark: The Chinese standard GB/T 43376-2023 is modified to adopt this standard to ensure that the surface treatment process is in line with international standards.

III. Key points of quality control of surface repair process

(1) Pretreatment requirements:
(1.1) Mechanical cleaning (sand blasting, shot blasting) to remove oxide scale and burrs.
(1.2) Chemical cleaning (pickling, degreasing) ensures that there is no organic contaminant on the surface.

(2) Repair process selection:
(2.1) Laser cladding: suitable for high-precision parts (such as blades), the thickness of the cladding layer and the heat-affected zone need to be controlled.
(2.2) Electroplating/chemical plating: used to restore conductivity or wear resistance (such as electronic devices).

(3) Post-processing and testing:
(3.1) Passivation treatment improves corrosion resistance and metallographic analysis verifies the density of the repair layer.
(3.2) Non-destructive testing (penetrant testing HB/Z 61) to check for microcracks or pores.

The aerospace industry has extremely high requirements for metal surface repair. The repair process must be selected in combination with the specific working conditions of the components, and quality control must be strictly followed in accordance with national standards (such as GB/T 43376), national military standards (such as GJB 10326) and international standards (such as ISO 8075). The key technologies involved include surface cleanliness, roughness control, corrosion resistance verification and mechanical properties testing.

We will provide technical services with the highest quality standards and solutions for corresponding complete sets of equipment based on the actual needs of our customers.